Vav Parallel Fan Failure - Trane Tracer Uc

Equipment Damage!
The UC400 controller outputs are switched to ground. Do not jumper 24 Vac to binary output
TRIAC(s) because damage will occur.
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VAV Parallel Fan Failure

Hazardous Service Procedures!
The maintenance and troubleshooting procedures recommended in this section of the manual
could result in exposure to electrical, mechanical or other potential safety hazards. Always
refer to the safety warnings provided throughout this manual concerning these procedures.
When possible, disconnect all electrical power including remote disconnect and discharge all
energy storing devices such as capacitors before servicing. Follow proper lockout/tagout
procedures to ensure the power can not be inadvertently energized. When necessary to work
with live electrical components, have a qualified licensed electrician or other individual who
has been trained in handling live electrical components perform these tasks. Failure to follow
all of the recommended safety warnings provided, could result in death or serious injury.
In the event that the fan output does not energize, check the following:
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VAV-SVX07B-EN
After all checks have been completed, check motor fan winding integrity and bearing failure.
Verify the output configuration in the UC400 controller setup screen. Unit needs to be
configured as parallel fan.
Outputs on the UC400 controller are configured as normally closed. Verify the output
configuration in the UC400 controller setup screen.
Note: Parallel fan can be enabled by either a differential temperature above the heating
setpoint or CFM flow.
Tracer SC has the fan output disabled. Ensure that the overrides are not inhibiting fan operation.
Note: For ECM fan there are two controlling outputs. The start/stop binary output and Analog
fan speed. If the fan speed is at 0% then the fan should be running at minimum flow The
status of the outputs can be checked on the TU binary status page.
A flow override exists locking out the fan output. Ensure that either Tracer SC or the Tracer TU
has released fan disable override. Flow overrides can be checked on the TU multistate status
page.
Note: If fan cycling is based on temperature or airflow, proceed to the next two bullet items.
If fan cycling is based on temperature and zone temperature is at or above the heating setpoint
plus heating offset on units configured as temperature control. A set differential of 0.5°F exists
to prevent short cycling.
– Increase the UC400 controller heating setpoint causing fan to cycle ON.
– Lower the heating setpoint by 6 degrees and the fan will cycle OFF .
If the fan cycling is based on airflow, the unit fan is energized whenever supply airflow is below
this setpoint. For this parallel fan configuration, the fan control point (if specified in a
percentage of unit airflow), must be set between 15% and 30% of the units cataloged airflow
to assure proper operation. A differential of 5% exists to avoid excessive fan cycling.
– Override damper closed until CFM is below enabled flow setpoint.
– Verify that the fan cycles ON.
NOTICE:
WARNING
Troubleshooting
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